1991 Ford F-150 Pickup Brake Service (ONLINE REPAIR MANUALS)

Make sure booster rubber reaction disc is properly installed as shown in Fig. , if the master cylinder pushrod is removed or accidentally pulled out. A dislodged disc may cause excessive pedal travel and extreme operation sensitivity. The disc is black compared to the silver colored valve plunger that will be exposed after pushrod and front seal are removed. The booster unit is serviced as an assembly and must be replaced if the reaction disc cannot be properly installed and aligned, or if it cannot be located within the unit itself.

• Disconnect battery ground cable.
• Disconn...

REMOVAL

• Raise and support vehicle.
• Remove wheel and tire assembly.
• On vehicles with full-floating axles, remove brake drum as follows:
• Loosen brake shoe adjustment screw.
• Remove rear axle retaining bolts and lock washers, axle shaft, and gasket.
• Remove wheel bearing locknut, lock washer, and adjusting nut.
• Remove hub and drum from axle.
• Remove brake drum to hub retaining screws, bolts, or bolts and nuts, then remove brake drum from hub.
• On vehicles with semi-floating axles, remove brake drum as follows:
• Remove brake drum retaining nuts.
• Remove brake drum. If brake lining is dragging on brake...

RAIL SLIDER CALIPER

Removal

• Drain a small amount of brake fluid from master cylinder reservoir.
• Raise and support vehicle, then remove wheel and tire assembly.
• Install an eight inch C-clamp on caliper housing and tighten clamp to bottom piston(s) in cylinder bore(s), then remove clamp. Do not use screwdriver or other edged tool to pry piston(s) from rotor.
• Remove key retaining screw, then using a hammer and drift, drive out caliper support key and spring.
• On single piston calipers, push caliper downward against spindle, then rotate upper end upward and out of spindle assembly.
• On dua...

Normal hydro-boost units will produce certain noises that current technology cannot correct. These noises occur when brake pedal is manipulated in a manner not associated with everyday braking habits. Normal operating noise can be a hissing, clunk, click or a chatter.

If above normal pedal efforts are applied, the hydra-boost unit will emit hissing noises. These noises will be particularly noticeable with the vehicle motionless and will increase in intensity as pedal efforts increase and system operating temperatures increase. Loud hissing noises at or below normal pedal effo...

The rear anti-lock brake system constantly monitors rear wheel speed. In the event of an impending rear brake lockup, the system regulates hydraulic pressure to the rear brakes, preventing total lockup when the brakes are applied and thereby reducing the possibility of skidding.

The system consists of a yellow warning light on the instrument panel, an electro-hydraulic rear anti-lock brake system (RABS) valve mounted on the frame rail behind the crossmember, a speed sensor mounted on the rear drive axle, an exciter ring mounted on the differential case and a comput...

EXCESSIVE PEDAL TRAVEL

• Worn brake lining.
• Shoe and lining knock back after cornering or rough road travel.
• Piston and shoe and lining assembly not properly seated or positioned.
• Air leak or insufficient fluid in system or caliper.
• Loose wheel bearing adjustment.
• Damaged or worn caliper piston seal.
• Improper booster pushrod adjustment.
• Shoe out of flat more than .005 inch.
• Rear brake automatic adjusters inoperative.
• Improperly ground rear brake shoe and lining assemblies.

BRAKE ROUGHNESS OR CHATTER; PEDAL PUMPING

• Excessive lateral runout of rotor.
• Rotor excessively out of parallel.

EXCESSIVE P...